I‘d get a 2nd opinion. Is this company planning on performing a leak check and reparing it? R22 is very expensive. $600 seems kind of cheap to find the leak, repair it and recharge the system, plus add a hard start. If they are just adding R22 and not finding and fixing the leak, its pointless. Any specifics on ”pulling to many amps” on startup? Thats pretty standard in compressor startup. How are the amps after startup when the system is stable? Its a personal choice and what you can afford. It is a pretty old system, so a repacement wouldn’t be a bad choice if you can afford it, but i would definately shop around.

Replace. You have no idea what will break next. We just did on our 18 year old heat pump. Well worth it. Much quieter.

If the coolant is low, the system has a leak. If more coolant is added, it still has a leak. If the leak is repaired, it's still 20 years old.

It's at or beyond the expected useful life for such equipment (as you've said) and it's acting as would be expected for something its age. The tea leaves in this case are easy to read.

I'd get a new one- now is a good time before summer weather hits and the HVAC contractors get busy.

Is the AC working well and keeping the house cool? If it is then it is not "really low" on coolant and it doesn't require a hard start kit. I suspect this tech is looking to either make some money on an unnecessary repair or sell you new equipment. If you plan on living in this house another 5 years then you should be planning on replacing the equipment. The only repair you might consider is a starter or run capacitor when needed. Anything beyond that is not a good investment in my opinion.

Is this system "really" not working?

A seasonal check up, you're getting someone who is out and about looking for work. In this case the unit is approaching end of life. 20 years old.

With the cost of R22 freon being what it is / cost of a hard start on top of that for $600? It doesn't sound to me like the unit is low on R22 Freon. If it was just Freon only --- $600? not likely.

If you want to evade a very likely summer break down then you can be proactive and replace.

However, there's more going on in the realm of HVAC these days. Anything new you buy now will use R410a which is a newer freon that we've used the past 20 years or so. Within the next few years (maybe sooner for some locations) R410a is on the chopping block to be phased out.

New refrigerants to take the place of R410a are R32 or R454b currently.

If your view is that R410a is better tested less risky of being a guinea pig for new tech, then buy a new system now. If that new system springs a refrigerant leak... and it will. The leaks will need to be repaired.

If I were you, I think I would pump the brakes and do a bit more homework. The thing is... there really is no wrong answer here... to wait and repair this old system or replace.

HVAC is complicated right now and only going to be more so as time goes on now. Whatever refrigerant comes next, those also will be phased out.

Want to buy another new air conditioner? The manufacturers and climate professionals of the world stayed up long hours to not only get your freon money, but also get your new equipment money.

I service the Katy, Texas area.

This video here is a starting point for the mess that is coming to a town / city near you.